Social Networks are Like the Eye: A Talk with Nicholas A. Christakis

This interview with Nicholas A. Christakis, a physician and sociologist, is about his investigations of the rules that determine the structure of social networks. For the last ten years, he has been studying social networks, investigating, for example, the spread of obesity through a network, the spread of smoking cessation through a network, the spread of happiness through a network, the spread of loneliness through a network, or the spread of altruism through a network. By considering social networks such as Facebook, MySpace, Flickr, and Twitter, he can study "social contagion" and both network formation and how networks operate.

Dr. Christakis suggests that social networks differ from other networks, which "are almost as interesting - networks of neurons or genes or stars or computers or all kinds of other things one can imagine - [in] that the nodes of a social network - the entities, the components - are themselves sentient, acting individuals who can respond to the network and actually form it themselves." He, along with colleague James Fowler, who has studied networks from a political science perspective, look at collective action in networks. He has concluded that: "In fact, I think that altruism is a key predicate to the formation of social networks because it serves to stabilize social ties. If I were constantly violent towards other people, or never reciprocated anything good, the network would disintegrate, all the ties would be cut. Some level of altruism is required for networks to emerge".


He cites that fact that telecommunications "digital traces" of evidence of people's networks now allows for the capture of data on a massive scale that "an be reapplied to investigate fundamental questions about social organization and about morality and other concerns that have perplexed us [social scientists] forever." He and James Fowler use data to think about the dynamics of networks, less about the architecture of networks - the static structure - and more about the processes of network formation, particularly understanding the processes of contagion.


According to the interview he is "interested not in biological contagion, but in social contagion. One possible mechanism is that I observe you and you begin to display certain behaviors that I then copy. For example, you might start running and then I might start running....Or you might start eating certain fatty foods and I might start copying that behavior and eat fatty foods... What spreads from person to person is a behavior, and it is the behavior that we both might exhibit that then contributes to our changes in body size. So, the spread of behaviors from person to person might cause or underlie the spread of obesity." He and colleagues examined data on the social network ties of 12,000 people over the course of the 32 years of data collection for the Framingham Heart Study. They found that weight gain or loss affected individuals by "rippling" through social networks and influenced "people up to three degrees removed from you in the network." They are testing ideas on the mechanism of that spread - biological ideas, for example, contagion, behavioural, and normative. "In our empirical work so far, we have found substantial evidence for the latter mechanism, the spread of norms, more than the spread of behaviors."

Dr. Christakis describes the internet as a "goldmine..."affirmatively organized as social networks — whereby people actually have formed and display their networks." By work on a longitudinal project limited to the social networking habits of Facebook users at one university he is studying the connection and contagion that take place with regard to the formation and operation of networks. For example, he argues that, though a Facebook user may have 100 - 200 friends in their network, they appear in photographs with fewer, perhaps 10 of them. These, he proposes, constitute a different set of relationships. He is able to trace the flow from person to person certain attributes like personal taste in music or fashion or the desire for certain privacy settings governing access to one's information. Through access to online social networks, he and his colleagues are able to examine both the topology of the network and the things that flow through the network as they seek to discover the rules that dictate the formation of networks and the flow of norms through them.